Several discrete lines of study on the structure and biosynthesis of airway mucin will be followed: 1. Cloning of the cDNA for the polypeptide core of human and canine tracheal mucin glycoproteins. Knowledge of the molecular weight of the deglycosylated materials coupled with the availability of antibodies directed against the proteins makes this feasible. Work will be initiated using an appropriate cDNA library and following identification, cloning and expansion, the cDNA sequence will be determined. The cDNAs thus obtained will be utilized for isolation of genomic clones which also will be sequenced. Clone identity will be confirmed by amino acid sequence analysis of selected peptide fragments. The latter data will also be continued with results of monoclonal antibody studies to prepare synthetic nucleotide probes from domains unique to the tracheal mucin glycoprotein. 2. Completion of the description of the organization of the macrostructure of the tracheobronchial mucins.